You may be having a typical Thursday, but the Earth is currently being blasted by a wave of radiation from a huge solar flare.

NOAA's Space Weather Prediction Center said the solar storm hit the Earth at about 2:45 a.m. PT. The solar storm is one of the strongest in years and could cause disruptions in satellites, affect radio communications in polar areas, and even slightly decrease the efficiency of solar panels.

This solar storm follows a similarly strong one only two months ago. Here's a short primer on what's going on.

First, are these solar storms dangerous?
In general, the physical danger is low and controllable. The biological hazard inherent in solar and geomagnetic storms comes from the exposure to radiation, which is mainly a concern for astronauts and people flying at high altitudes, according to NOAA's ranking of storm severity.

On the other hand, the disruptions that more severe storms can cause have the potential to bring about real damage. Milder storms may disrupt the satellites that handle GPS communications. But the more severe geomagnetic storms can spike the voltage in transmission lines which could damage grid transformers and potentially knock power out. A massive power outage in the province of Quebec in 1989 was blamed on a solar storm.

What's happening with today's storm?
Today's storm is predicted to reach G3, which is a strong level. The solar radiation is at S3, also strong, and there was a strong-level radio blackout. NOAA this morning noted that "so far the orientation of the magnetic field has been opposite of what is needed to cause the strongest storming." Space forecasters will be closely watching this event as they go on for days.

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The increased radiation, which collects along the Earth's poles, means that flights will likely be rerouted to avoid the North Pole, as some were earlier this year. Grid operators have also been notified to monitor potential power surges, according to NOAA.

The influx of super hot gases from the sun hits the magnetic field that protects the Earth and causes the waves of energy and particles to flow toward the poles and collide with the atmosphere. This causes fantastic, multi-hour displays known as auroras. These type of events bring out stargazers to watch the stunning green glow caused by the solar flare in northern countries.

What causes them?
The sun is a big ball of burning gas and solar flares are loop-like explosions at the surface. Solar flares often occur at the same time as coronal mass ejections (CMEs), where a chunk of the sun breaks off from its atmosphere. The biggest flares can be tens of times the size of the Earth. When there is a coronal mass ejection, high-energy particles can travel at over 1,000 miles per second. This solar flare was caused by two CMEs on Tuesday and passed by several NASA spacecraft, according to NASA. There were also two CMEs caused by a solar flare on Sunday, NASA said.

When a CME dumps its solar particles and magnetic fields into the Earth's atmosphere, it distorts the Earth's magnetic fields and causes a geomagnetic storm, the source of potential grid disruptions.

Often, solar flares are too weak to be noticed or they don't move directly toward the Earth as is happening today. The biggest flares are X-class flares, which is what happened earlier this week. In 2006 an X-class flare caused a CME that interfered with GPS signals being sent to ground-based receivers. That's why operators of aircraft, satellites, and grid monitor the space forecast to take steps to avoid problems.

What's the forecast?
The reason we're hearing more about solar flares is because we are moving toward a "solar maximum," a period of increased solar activity. These cycles, which are on average 11 years, mean an increase in the number of solar flares. The next maximum is expected in 2013, according to NASA. These cycles are analogous to seasons on Earth.

In addition to disruptions in radio communications and GPS systems, NOAA says that many smaller problems are possible with the uptick in solar activity. Specifically, many devices used for scientific experiments, such as measuring ozone and magnetic sensors for mapping fault lines and the ocean floor, could be impacted.

What are the chances for a really big one?
Some space weather scientists argue that society and the economy need to be better equipped to predict or deal with a more severe event caused by solar activity.

The most well known severe event is called the Carrington Event of 1859, which experts now believe was two intense geomagnetic storms. The event caused disruptions in telegraph networks and green and white auroras were seen in many places around the world. According to a paper from 2011, telegraph operators disconnected their batteries and used the influx in current from the auroras to send messages. The economic costs today of such an event could be trillions of dollars, according to a 2009 U.S. House Homeland Security Committee.

Last month, space weather scientist Pete Riley published a paper that used statistical methods from other fields to try to ascertain the likelihood of another Carrington-like event. The results were not comforting: he found the chances of another extreme space weather event are 12 percent in the next decade, or one in eight. "The 12 percent number was a surprise; certainly to me, and to others I suspect," Riley told CNET.

Updated on March 10 with correction. Solar flares do not cause CMEs, although CMEs often occur at times of high solar activity.

About the author

Martin LaMonica is a senior writer covering green tech and cutting-edge technologies. He joined CNET in 2002 to cover enterprise IT and Web development and was previously executive editor of IT publication InfoWorld.
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